1. Field of the Invention
The present invention relates to a novel method for effecting recovery and production of oil from oil containing masses and formations by contacting such masses or formations with foul condensates; i.e., black liquors, from paper and pulping operations thereby unexpectedly freeing the oil present in and/or bound up in such masses. The process is particularly effective and suitable for stimulating the production and recovery of oil from earth formations and strata wherein paraffinic deposits permeate and clog the fissures and channels in the formation thereby reducing or even stopping the flow of oil towards a well bore.
2. Description of the Prior Art
The technical and patent literature is replete with descriptions of processes and procedures for stimulating the recovery of oil from oil bearing masses and formations. Hydraulic fracturing techniques, both with and without the use of propping agents, in which a pumpable aqueous liquid is forced under pressure into a formation to generate new fissures and enlarge existing ones are standard practice. Water is the principal fluid used in such operations.
Primary and secondary water drives for forcing oil through fissures towards boreholes of wells are well established procedures for recovering oil from fields in which primary production has dropped below levels conducive to economic recovery.
The use of mineral acids, particularly inhibited hydrochloric acid, has been practiced for many years in the cleaning and finishing of wells following completion of drilling operations.
Currently employed techniques for keeping oil bearing formations free from fissure clogging paraffins involve the use of carbon tetrachloride or carbon disulfide as deparaffining agents. These procedures require the handling and pumping of large quantities of the agents which have been shown by recent studies to be carcinogens. Additionally, carbon tetrachloride for many years has been known to cause irreversible liver damage when its fumes are brought into the human body. Because of these deterrents to human health, it can be expected that their use in such operations may well be stopped through regulatory means.
Much time, effort and enormous sums of money are being spent in an effort to utilize underground, in situ fire drives or retorting techniques on oil shales and tar sands to obtain oil values therefrom. Steam treatment and retorting of these materials in above ground plants also is being investigated, but neither of these techniques has proved to be either technically nor economically practical to date in pilot or large scale operations.
Waste foul condensates, commonly called black liquors because of their dark color, result as an undesirable waste by-product from paper mill operations, both kraft and non-kraft. Generally, these liquors are the condensate from evaporators and surface condensors associated with pulp digesters. These liquors heretofore have had no recognized use and their disposal in itself has been and continues to be an ever increasing problem. In the past, these liquors have been diverted into streams, rivers and lakes where they have given an undesirable dark color to the water body, imparting an objectionable odor and taste to the water and tainted the flesh of the fish and other edible life inhibiting such lakes, rivers and streams. Recent strengthening of environmental impact regulations has placed an ever increasing burden on mill operators to legally and properly dispose of such waste liquors by other means.
Blackwell, MacKay, Murray and Oldham, "Review of Kraft Foul Condensates", Tappi Vol. 62, No. 10, October 1979, summarizes the sources, quantities, chemical composition and environmental effects of such liquors and presents an extensive bibliography of the published literature about such waste liquors and the problems they present, particularly when the liquors are introduced into fresh water bodies and streams for disposal.
More recently, in the United States, mills have been recycling the black liquors which contain about 35 percent organics to cookers until the liquors are condensed to a mass containing about 65 percent organics with the balance being inorganic matter and residual water. This mixture then ordinarily is subjected to combustion on a fluidized bed to remove the organic matter but this process of waste disposal has been beset with problems.
Applicant is unaware of any literature or patent publications in any way related to or suggesting any practical use of waste foul condensates; and, in particular, for effecting oil recovery from oil bearing masses.